This invention is directed generally to the zinc galvanizing arts and more particularly to a new and improved method and apparatus for obtaining a bright finish on zinc galvanized wire.
In many applications it is desirable to provide a bright finish on galvanized wire, as opposed to the relatively dull surface appearance normally imparted during the conventional galvanizing process. For example, where the wire is visible in the products and/or situations in which it is utilized, it is often considered desirable to have a bright or shiny finish.
It is known in the prior art that such a bright or shiny appearance or finish may be obtained by water quenching the wire while the zinc coating applied thereto in the galvanizing process is still in a molten condition. However, many problems have been encountered in facilitating such water quenching in conjunction with the conventional galvanizing process and apparatus. For example, such water quenching requires that the wire be delivered from the surface of the molten zinc galvanizing bath to the water quenching mechanism very rapidly, before the zinc coating has had a chance to cool and solidify. If the zinc coating should begin to solidify prior to reaching the water quenching apparatus, the water quenching will not perform its desired function and the finish will be dull.
In one prior art system a water quenching tank is positioned in close proximity to the surface of the molten zinc galvanizing bath. Such installations have met, however, with a number of problems and disadvantages. For example, in many such installations extensive modifications were required in the structure of the conventional galvanizing apparatus. In many cases, the walls of the zinc bath were modified to provide access for water pipes or the like at a sufficiently close level to the exit point of the wire from the surface of the molten zinc. Such modifications are generally difficult and expensive. Moreover, such arrangements introduce a distinct possibility of leakage of water from the quenching bath into the molten zinc with resultant explosive vaporization. Moving the water quenching bath far enough from the surface of the molten zinc to prevent such water leakage generally results in excessive degree of resolidification of the zinc coating before the wire reaches the water quenching bath. In another prior art device, a seal for water leakage prevention, through which the zinc coated wire passes prior to entering the water quenching bath, causes accretion of a "blob" or globule of molten zinc at the entrance of the seal as the wire passes through. This accretion of molten zinc at the entrance to the sealing mechanism tends to resolidify as it grows in size, thus offering undesireable resistance to the feeding of the wire through the galvanizing apparatus, to the point of causing breakage of the wire. This is clearly undesirable as it would require shut-down of the apparatus to restart wire therethrough in a continuous strand, in the conventional fashion.